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술폰화 poly(arylene ether sulfones) 양이온 교환막의 술폰산기 농도 변화에 따른 특성
김래현,이승용,최선용,이정우,박세용,Kim Lae Hyun,Lee Seung Yong,Choi Sun Yong,Lee Joung Woo,Park Sei Yong 한국전기화학회 2000 한국전기화학회지 Vol.3 No.1
이온 교환막의 고정이온 농도변화에 따른 막 특성을 알아보기 위해 matrix인 PSF (polysulfone)과 술폰화제인 CSA(chlorosulfuric acid)의 몰 비를 달리하여 SPSF (sulfonated polysulfone) 양이온 교환수지를 합성하였다. 합성된 SPSF의 이온교환용량, 함수율, 고정이온 농도, 분배계수 등을 측정하였다. DSC, TGA분석으로부터 SPSF의 술폰산기 농도 증가에 따라 벌키한 술폰산기의 도입으로 인하여 유리전이 온도는 증가하고 중량 감소비는 감소하는 것으로 나타났다. 본 실험조건에서는 SPSF막의 구조가 SEM, AFM등의 분석을 통하여 비대칭인 것으로 나타났다. 교류 임피던스로부터 측정한 SPSF 막을 통한 $Na^+$ 이온의 겉보기 확산계수는 술폰산기 농도 증가에 따라 증가하였다. Sulfonated Polysulfone (SPSF) cation-exchange membranes were synthesized by introducing various ratio of chlorosulfuric acid (CSA) onto the main chain of polysulfone (PSF). Properties such as ion exchange capacity, water content, liked ion concentration, and partition coefficient were measured, respectively. Through the analysis of DSC and TGA, it has been shown that glass transition temperature increased and weight loss decreased as sulfuric acid group concentration increased. Structure of membrane measured by AFM and SEM was seen to be asymmetric. Apparent diffusion coefficient of sodium ions through SPSF membrane by AC impedance was increased as sulfuric acid group concentration increased.
"작은 생물의 세계" 수업 주제에 대한 초등학생들의 후속흥미 분석
김래현 ( Lae Hyun Kim ),임채성 ( Chae Seong Lim ),김재영 ( Jae Young Kim ) 한국생물교육학회 2014 생물교육 Vol.42 No.4
Interest is one of the most important factors in science education. The issue that most students are not interested in science so much has been actively discussed by many researchers until now. However, most studies have addressed about factors of students`` interest and analyzed process of interest. This study analyzed elementary school students`` interests after regular science lessons of Small Organisms`` World. The follow-up interests of the students on the topic were grouped into three categories: the extended-developed-deepened (EDD) type, the simply expanded-maintained (SEM) one and stoped or decreased (SD) one. These categories had specific distinguishing features. The EDD type contained detailed and creative descriptions, which are individually different, and was associated with need for cognition, prior knowledge, subsequent science learning, and individual student``s experience. Additionally, the students who belong to this category generated scientific questions on the basis of observations during their science lessons. SEM type had something in common, not specific, simple redescription of prior class activities. So they did not expand or apply what they have learned to new situation or area. The SD type consisted of the simple copies of what they have learned or short-answers. The reasons for their answers were not appropriately addressed because they didn``t have any interest on the topic. Most of the follow-up interests of the students on Small Organisms`` World were related to situational interest rather than individual interest. Based on these findings, implications for supporting students`` interests on scientific topics in science teaching and learning situations are advanced.
작은 생물의 세계 주제에 대한 초등학생들의 후속 흥미에 영향을 미치는 요인 분석
김래현 ( Lae Hyun Kim ),임채성 ( Chae Seong Lim ) 한국초등과학교육학회 2016 초등과학교육 Vol.35 No.1
Interest is one of the important factors in science education. The purpose of this study was to investigate factors affecting the follow-up interest of elementary school students on topics of ‘Small Organisms` World’. The follow-up interests of the students on the topic were grouped into three categories; the developed-expandeddeepened (EDD), the simply expanded and maintained (SEM), and the stoped or decreased (SD) types. Each types had specific distinguishing features. Through the examination of students` responses and the in-depth interviews, the factors affecting on the follow-up interests of the students were analyzed. The factors were classified into two types of the external factor and the internal one. While the external factors were mainly related to the instructional materials used in science class and teaching methods, the internal factors were related to the desire for knowing, prior knowledge, students` experience and attitude toward the topics of science. In relation to the types of the follow-up interests, these factors were affected by different causes. The EDD type was most affected by internal factors, such as desire for knowing and prior knowledge. The SEM type was shown to be most affected by external factors, such as instructional materials. The SD type was mainly influenced by external factors, such as teaching methods. From the analysis of internal factors, it was revealed that the attitude and the prior knowledge about the topic are related with the follow-up interests. There was a positive relationship between the levels of science attitude and science knowledge. The students who had EDD type had a higher level of attitude and knowledge. However, there were some students who had higher level of scientific knowledge with SD type. The results of in-depth interviews showed that they were influenced by negative perceptions about science and stress on their grades. In conclusion, each follow-up interest type were caused by the external factors contained in the processes of the science class and the internal ones associated with the individual features and were influenced by the science class. So, the teacher should help the students be able to have the EDD type of follow-up interest which is persisted even after the completion of the science curriculum. For this, when the teachers design science curriculum and plan lesson, they should consider both internal and external factors significantly influencing the students` follow-up interests.